Process for preparing stable peroxidecontaining borates



V Haber-nickel,

S ates Patent PROCESS FOR PREPARING STABLE PEROXIDE- CONTAHYING.BORATESi for a long time been the endeavor to make such products which have acomparatively high content in peroxidewhich can also be expressed by thecontent of active oxygen-and which are particularly stable. The objecthas mainly been carried out by adding stabilizers to the perborates.

More recently the discovery has been utilized that products with highalkali content are unstable and therefore borates were made containingperoxide in which the ratio of B O :Na O is about 1:0.5-0.9.

It has now been found quite unexpectedly that with a suitable method ofpreparation, stable peroxide-containing 'borates can be made in whichthe molar ratio and which have a content in active oxygen of more thanThe preparation is done by making a solution from the conventionalcomponents, e.g. boric acid, NaOH, and hydrogen peroxide in theappropriate molar ratio; instead of the components named, equivalentamounts of similar starting materials may be used for making thesolution 3 which is prepared at low temperature and which is then passedover surfaces heated to IOU-130 C.

Instead of using boric acid, NaOH and H 0 the equivalent amountof, forinstance, the several borates (such as metaborate, borax) may be usedwith NaOH and H 0 instead of the components named it is also possible touse Na O and H 0 either with boric acid and NaOH or with borate. Theamount of H 0 is preferably so taken that about 1.7-2.4 mol arecalculated for 1 mol of Na O. In

' preparing the solutions from the components it is advantageous not toexceed temperatures of 26-30" C. at the utmost. It has also provenadvantageous to use heated rollers for the subsequent heat treatment ofthe solution. In this manner products are obtained having a content inactive oxygen between 15 and these products have high stability withoutthe addition of any stabilizer.

The products so obtained, which are by the Way not crystalline, show avery much improved solubility amounting to many times the solubility ofconventional perborate. In spite of a similar analytical composition,the products according to the invention are therefore essentiallydifferent in their properties from mixtures of sodium perborate and Na Oobtained bysimple mixing. The products made according to the inventionmay be used in bleaching, laundering and cleansing agents per se or inadmixture with known additives;

In some cases it is desirable to make the addition of substances whichare useful for even liberation of oxygen in laundering and bleachingagents, already in the preparation of peroxide-containing borates. Byprocessing in this manner, a better and more thorough mixing action isfrequently obtained.

7 As such additions I may mention e.g. magnesium salts,

more particularly magnesium silicate, waterglass, or mixtures thereof.These compounds are also known as stabilizers, in order to preventperoxide decomposition during storage. However, an additionis notnecessary forstabilizing purposes in the peroxide-containing borates,

when made according to the present invention, when the products are notintended for "long-timestorageg The process according to theinventionwill now bemore the H 0 is all entered, a clear solution isformed which is sprayed in a thin layer on a roller drier and isevaporated to dryness at a temperature of -11-0 C.

Yield: 8490 g. dry powder with 18.9% active oxygen.

Analysis: 34.2% Na O; 24.9% B 0 40.0% H 0 pH value in 1% solution=10.99.

Solubility 48 g. in 100, cc. H O at 35 C.

After 3 months storage at 25 C. the active oxygen had dropped to 18.75%.

Example 2 4270 g. boric acid are mixed with 4200 g. caustic soda (molarratio B O :Na O=1.52) at 25 C. and into the mixture 8.22 liters of 40% H0 are poured, whereupon the solution is processed according to Example 1on a. roller drier at C.

Yield: 9000 g. dry, amorphous powder with 17.4% active oxygen. 7

Analysis: 36.1% Na O; 26.6% B 0 37.0% H 0 pH value in 1% solution=11.20. Active oxygen after three months: 17.30.

Example 3 2920 g. boric acid and 4300 g. caustic soda (molarratio B O:Na 0=1:1.69) are dissolved in 7.76 liters of 40% fifg cand evaporatedto dryness on a roller drier alt Yield: 8630 g. with 16.9% activeoxygen.

Analysis: 38.5% Na 0; 25.6% B 0 35.95% H 0 pH value in 1% solution=11.3.

Solubility 34 g. in 100 cc. H O at 35 C.

Oxygen content after 3 months at 25' 6:16.75.

Example 4 4050 g. boric acid are mixed with 4000 g. caustic soda (molarratio B O :Na O=1:1.54) and are slowly poured while stirring in 3000 cc.water. The temperature rises to 100 C. while a clear slightly syrupysolution is formed. The solution is cooled down to 70 C., care beingtaken that a premature solidification is avoided. The solution is thenpassed into 8.2 liter-s of 40% H 0 cooled to 010 C. To the clearsolution, 200 g. of magnesium silicate powder are added and theresulting product is hereafter quickly evaporated on a roller drier atC.

8500 g. of a borate containing active ogygen are obtained, the activeoxygen content (17.6%) being practically unchanged after 12 months.

Analysis: 35.9% Na O; 26.0% B 0 37.7% H 0 pH value in 1% solution=11.30.

Example 5 1965 g. boric acid and 2155 g. caustic soda (molar ratio B O:Na ()=l:71) are stirred with 1.5 liters water. The

solution is slowly poured into 3.88 liters of 40% H 0 at 10-20 C. Tothis solution are finally added 430 g. waterglass of 40 B. (8.83% Na29.35% SiO 61.82%. H 0) and is further processed as described in Example4.

P t lt fl' M rk 24 1 50 Yield:4480 g. with 16.3% active oxygen.

Analysis: 37.3% Na O; 24.3% B 34.6% H 0 pH value=11.3.

Oxygen after 2 months=16.20. --WhatIclaimis:" 1.-;A process forpreparing stable solid peroxide-containing 'borates, which comprisesmaking an aqueous solution of a boron compound, selected from the groupconsisting' of boric acid, borax and metaborates, NaOH and H 0at'temperatures of 0-30 C., in a molar ratio of B 0 calculated on theboron compound present, to Na O of approximately 1:1.1-2, and of H 0 toNa o of approximately 1.7-2.0:1, and conducting said solution overheated surfaces at a temperature ranging from 100-130" 0., whereby a dryborate having an active oxygen content of more. than 15 percent isobtained which will not decrease during storage, said borate being aneffective laun- 4 dering, cleansing and bleaching agent usable by itselfwithout addition of other agents.

2. A process according to claim 1, wherein the solution is passed overrollers heated to LOO- C.

References Cited in the file of this patent UNITED STATES PATENTS1,978,953 McKeown Oct. 30, 1934 2,152,520 Lind Mar. 28, 1939 2,367,971Spiegler J an. 23, 1945 2,397,193 Miller Mar. 26, 1946 2,491,789 YoungDec. 20, 1949 FOREIGN PATENTS 1,016,620 France Aug. 27, 1952

1. A PROCESS FOR PREPARING STABLE SOLID PEROXIDE-CONTAINING BORATES,WHICH COMPRISES MAKING AN AQUEOUS SOLUTION OF A BORON COMPOUND, SELECTEDFROM THE GROUP CONSISTING OF BORIC ACID, BORAX AND METABORATES, NAOH ANDH2O2 AT TEMPERATURES OF 0-30*C., IN A MOLAR RATIO OF B2O3, CALCULATED ONTHE BORON COMPOUND PRESENT, TO NA2O OF APPROXIMATELY 1:1.1-2, AND OFH2O2 TO NA2O OF APPROXIMATELY 1.7-2.0:1, AND CONDUCTING SAID SOLUTIONOVER HEATED SURFACES AT A TEMPERATURE RANGING FROM 100-130* C., WHEREBYA DRY BORATE HAVING AN ACTIVE OXYGEN CONTENT OF MORE THAN 15 PERCENT ISOBTAINED WHICH WILL NOT DECREASE DURING STORAGE, SAID BORATE BEING ANEFFECTIVE LAUNDERING, CLEANSING AND BLEACHING AGENT USABLE BY ITSELFWITHOUT ADDITION OF OTHER AGENTS.